FR2755154A1 - WEFT YARN SELECTION DEVICE FOR WEAVING - Google Patents

Abstract

This device comprises needles (20) each having an eye (22) through which a weft yarn (8) passes. The needles (20) are arranged parallel to one another, all the needle eyes (22) being located on the same side. Means (56, 60) are provided for displacing one needle (20) longitudinally relative to the others between an inoperative position and a selecting position. The device comprises a weft yarn guide (70), arranged between the inoperative position and the selecting position of the needles for converging a weft yarn (8) towards a predetermined position when a needle (20) moves from the inoperative position to the selecting position.

Description

 The present invention relates to a device for selecting weft threads for a loom.

 In a loom, during weaving, weft threads pass between warp threads which are mounted on the loom. To make designs of different colors on the piece of fabric produced, the weft thread changes so as to obtain the desired effect.

 The warp threads are generally located on a roller called beam and arranged at the rear of the loom.

The number of warp threads depends on the capacity of the trade and the types of fabrics to be produced. Generally there are several thousand warp threads on a loom.

 The weft threads are generally wound on cones. These are usually placed on a support called a creel which is next to the loom.

 To weave a piece of fabric, weft threads are passed between the warp threads. Some of these are pulled up, others down, either by a jacquard device or by a frame system (dobby), thus leaving between them a passage called the crowd. For each stroke of the trade, a weft thread passes through the crowd.

 To pass a weft thread through the crowd, we must first select the thread, among those present on the creel, which will pass through the crowd, then we must then insert this thread into the opening of the warp threads .

 To select a weft thread, it is brought to a very precise place where a mechanical vector comes to grab it. The mechanical vector is most often constituted by a clamp, but other techniques are known: the wire can for example be driven by a projectile, or else a drop of water or even a flow of air.

 Most of the weft yarn selection devices currently known allow four to eight weft yarns to be selected. These devices include a set of needles having an eye in which a weft thread is threaded. These needles are arranged in a fan in a plane and each move longitudinally towards the point of intersection of their axes.

 By combining two selection devices, it is also known to have a selection device that can choose up to sixteen weft threads. The size is then very important and it is difficult to manage the space in which the device is located in order to be able to converge in the same very restricted area sixteen separate weft threads. Indeed, the known mechanical or electro-mechanical devices are complex and the need to present a weft yarn in a very precise zone limits the number of possible selection paths.

 The object of the present invention is therefore to provide a new device for selecting weft threads which allows, in a small space, to select a larger number of threads.

 To this end, the device for selecting weft threads for a weaving loom which it offers is a device comprising needles each having an eye through which a weft thread passes.

 According to the invention, the needles are arranged parallel to each other, all the needle eyes being on the same side; means are provided for longitudinally moving a needle relative to the others between an inactive position and a selection position, and the device comprises a guide for weft thread, disposed between the inactive position and the selection position of the needles and causing a weft yarn to a predetermined position when a needle passes from the inactive position to the selection position. This guide may be integral with the device or else be fixed close to it.

 This arrangement of needles makes it possible to have a compact device, easy to manage. As for the guide, it allows the weft threads to be guided, when they pass from the inactive position to the selection position, towards a position where they can be gripped by pliers or be taken by any other means enabling a weft thread through warp threads.

 In a preferred embodiment, the guide consists of a V-shaped rod, the point of the V being oriented towards the position for selecting the needles. Other embodiments are possible. The guide can for example be formed by plates converging towards one another.

 To facilitate their selection, the needles are advantageously provided with a hook at their end opposite the eye. In this case, the device is preferably provided with a hook selection device.

 The hook selection device is advantageously provided with counter-hooks which are controlled so as to move between two positions, a selection position in which the hook and the corresponding counter-hook can be engaged with each other and a position of non-selection not allowing such a hold.

The device can for example be a device such as that described in document EP-0 108 700 but it is preferably a device such as that described in the patent application not yet published on the date of filing of the present request and number
FR-95.08767. In this case, the hook selection device comprises parts provided with a lug or counter hook, each of these parts corresponding to a hook and the position of the lug relative to the hook being controlled by an electromagnetic device having at least one coil, so that, when the element carrying the needles moves away from the selection device, the lug, depending on its position, is engaged or not with the hook. Each part provided with a lug is a rigid blade comprising at least one part made of magnetic material, pivotally mounted around an axis. The selection device comprises means for creating a permanent magnetic field at the part made of magnetic material of the blade, and the coil makes it possible to act on the part of the blade made of magnetic material, so that, according to the polarities of the coil and the permanent magnetic field, the blade pivots about its axis either in a first position allowing it to be engaged with the corresponding hook when the needle moves away from the selection device, or in a second position not allowing such training.

 Such a selection device allows a very quick selection of hooks and very reliable. In addition, the energy consumption of this device is low.

 An advantageous embodiment provides that the needles are made of a magnetic material, that the weft thread selection device comprises a magnet extending perpendicular to the needles and acting on each of them, and that the magnet is movable with respect to the longitudinal direction of the needles and drives the needle through which the selected thread passes. Thus the permanent magnet allows the drive of the selected needle without requiring a return spring. The mechanics of the system are therefore simplified.

 In the previous embodiment, the magnet is advantageously mounted on a mobile carriage guided by two guide columns parallel to the needles and placed on either side thereof. The mobile carriage then preferably also carries a needle guide in the form of a comb and faces a friction plate throughout its travel. The needles are thus perfectly guided by the needle guide and the friction plate and the magnet hold the needles in the desired position.

 When the device comprises a mobile carriage carrying a permanent magnet and a hook selection device, the needles advantageously have a shoulder near the hooks so that at the end of the travel of the mobile carriage, when the latter moves in the direction of the hooks, all the needles are positively driven by the mobile carriage. It is thus ensured in the inactive position that no stress is exerted on the device and it is then possible to vary the configuration of the hook selector.

 In this latter embodiment, it is also advantageous to provide that each needle is prestressed when it is in the inactive position by a spring acting in the direction of movement towards the eye of the needles. Advantageously, the device according to the invention also comprises a needle positioning detector in order to ensure synchronization between the position of the needles and the selection of hooks operated by the hook selection device.

 When the device according to the invention comprises a mobile magnet, the reciprocating movement of the latter is preferably obtained by transformation of a circular movement.

 In any case, the invention will be clearly understood with the aid of the description which follows, with reference to the appended schematic drawing representing a preferred embodiment of the invention.

FIG. 1 is a perspective view showing a weaving loom equipped with a weft thread selection device according to the invention,
FIG. 2 is a front view on an enlarged scale of the device according to the invention, this device not being provided with its cover,
Figure 3 is a sectional view along the section line III-III of Figure 2, and
Figure 4 is a sectional view, on an enlarged scale, along the section line IV-IV of Figure 2.

 A jacquard weaving loom is shown in Figure 1. On this loom are mounted, in a manner known to those skilled in the art, warp threads. They are wound on a roll called a beam which is arranged at the rear of the loom and which is therefore not visible in the drawing. These chain threads, several thousand in number, extend towards the front of the machine and form part of the piece of fabric 2 shown in FIG. 1.

The piece of fabric 2 is wound on a roller placed under the machine as the weaving progresses.

 Each chain thread passes through the eye of a needle. This is controlled via a control wire 4 by a selection device 6 disposed in the upper part of the loom. In a weaving loom with a frame system, the selection device would be in the rear part of the loom. It is thus possible to pull a chain thread upwards or to bring it down downwards. When all the warp threads are either pulled up or down, a passage appears between the warp threads. This passage is called the crowd.

 To weave the piece of fabric 2, weft threads 8 are passed through the crowd. The weft threads 8 pass one by one between the warp threads. Between two successive passages of a weft thread, or stroke of the loom, the selection of warp threads varies.

 By changing the position of the warp threads and modifying the color of the weft thread 8, it is possible to make designs on the piece of fabric 2.

 The loom shown is intended for weaving pieces of fabric with designs and uses several weft threads 8 of different colors. The weft threads 8 are each wound on a cone 10 and all the cones 10 are arranged on a support called a creel 12 and placed next to the loom.

 All the cones 10 are connected by the weft thread 8 corresponding to the loom. During weaving, with each stroke of the loom, a lance (not shown), provided with a clamp at its end, comes to pick up the weft thread 8 and passes it through the crowd.

 Of course, it is necessary to each weaving loom select the weft thread 8 which will be taken by the lance and its clamp to make the next row. A selection device 14 is provided for this purpose. This device is placed on the loom and is located on the side of the creel 12.

 The selection device 14 makes it possible to move the selected weft thread to a very precise and predetermined position where the lance and its clamp will pick it up. Generally, only one weft thread is selected at a time. However, it is possible to select for very specific applications, two weft threads 8.

 The weft yarn selection device 14 according to the invention is described in more detail below with reference to FIGS. 2 and 3.

 This device comprises a housing 16 provided with a cover 18, needles 20, a device for selecting needles as well as a device allowing the displacement of the selected needle 20.

 The needles 20 are arranged parallel next to each other in the housing. At one of its ends, each needle 20 has an eye 22 while it has a hook 24 at its other end. These needles 20 are made of a magnetic material, steel for example. The hooks 24 and the eye 22 do not necessarily form an integral part of the needle 20 and can for example be molded parts made of synthetic material.

 In the following description, we will assume that all the needles 20 are arranged vertically and oriented so that the eyes 22 are at the bottom and the hooks 24 at the top, it being understood that the device can work very well in any other orientation .

 On the side of the hooks 24 and facing them, there is a row of counter hooks 26, each counter hook 19 corresponding to a hook 24. These counter hooks belong to a device 28 for selecting hooks. This device is for example a device as described in document EP-0 108 700 or preferably in French patent application FR-95.08767 not yet published at the time of filing of this patent application. This last document discloses a device 28 for selecting hooks as described below with reference to FIG. 4.

 Each counter hook 26 constitutes the end of a blade 30. The blades 30 are pivotally mounted in a housing 32. Each blade 30 is equipped with a transverse axis 34, mounted on bearings 36 formed on a wall of the housing 32 .

 The blades 30 have a housing 38 on the side opposite the hook-hook 26. A permanent magnet 40 is placed between two pole pieces 42 inside this housing 38. One end of each pole piece 42 projects from this housing.

 Opposite the blade 30, on the side of the magnet 40 and of the pole pieces 42, are an armature 46 and a coil 44. The latter can be traversed by a direct electric current. An electronic card 50 comprising a printed circuit manages the passage of current through the coil 44.

 The frame 46 has the shape of an E whose branches are oriented towards the blade 30. Between two branches of the E, there is each end of a pole piece 42. The central branch of the E carries the coil 44 .

 An air gap 48, made of a non-magnetic material, is placed on each side of a branch of the E facing a pole piece 42.

 The operating principle of this hook selection device is described below.

 The polarity of the middle arm of the armature depends on the direction of the current in the coil 44. The polarities of the two lateral arms of the armature are opposite to the polarity of the middle arm. The polarities of the two pole pieces do not vary and they are opposite.

 At equilibrium, whether current flows through the coil 44 or not, each pole piece 42 abuts against the end of a branch of the armature 46. If current flows through the coil 44, in the opposite direction at the last current flow, the polarity of the central arm of the armature varies, as well as that of the lateral branches. The pole piece 42 abutting against the middle branch of the frame is then pushed back by the middle branch of the frame, but also attracted by a lateral branch. The same goes for the other pole piece, which is pushed back by the lateral branch against which it rested and which is attracted by the central branch.

 The air gaps 48, made of non-magnetic material, make it possible to adjust the force of attraction between the pole pieces 42 and the branches of the frame 46.

 The blade 30 of the hook selection device can take two stable positions: one corresponds to the selection of the corresponding hook 24, the other to the non-selection thereof.

 In the absence of current in the coil 44, the blade 30 remains in the position in which it is, both in the selection position and in the non-selection position. As long as a new electromagnetic field generated by a current of opposite direction in the coil 44 does not come to modify the polarity of the branches of the armature 46, the blade 30 remains in a stable position.

 In this device, a few milliseconds are enough to cause the blade 30 to tilt from one position to the other. The selection of the hooks 24 can therefore be carried out quickly. As a result, energy consumption is minimized.

 An electronically managed memory makes it possible to store all the configurations necessary for the production of a pattern on a loom equipped with this device. This memory can for example be on a memory card. A reader makes it possible to read the content of this memory and provides the information stored in the electronic card 50 of the selection device 28 of the hooks.

 The housing 32 of the hook selection device is fixed in the housing 16 of the device according to the invention by means of supports 52 which make it possible to position and maintain the selection device 28 for hooks.

 On either side of the row of needles 20, and slightly offset with respect thereto, there are two guide columns 54. The latter extend parallel to the needles 20, that is to say vertically. They are fixed in the housing 16 by their two ends so as to form a rigid guide.

 On these two guide columns 54 is mounted a sliding carriage 56 which essentially carries two needle guides 58 in the form of a comb and a permanent magnet 60. Each needle 20 passes between two teeth adjacent to each needle guide 58. A friction plate 62 mounted on the cover 18 holds the needles 20 between the teeth of the needle guides 58.

The magnet 60 also retains the needles 20 by preventing them from falling.

 Thus, when the carriage 56 moves along the guide columns 54, it carries with it the needle 20 which has been selected, that is to say the one for which the counter-hook 26 is not facing the hook 24 The other needles 20 are retained by their hook 24 by means of the counter hooks 26 of the hook selection device 28. Thus FIG. 2 shows the carriage 56 with a needle 20 in the low position. In FIG. 3, the carriage 56 and all the needles are in the high position.

 When the carriage arrives in the high position from the low position, it drives with it at the end of the race all the needles 20 so as to leave a clearance between the hooks 24 and the counter hooks 26. A shoulder is provided on the needles 20 at level of the hooks 24 (FIG. 3), the base of the hook 24 being wider than the body of the needle. This allows a positive drive of the hook 24 and therefore also of the needle 20 which is integral with it by the carriage 56.

 In fact, it is when the carriage is in the high position that the hook selection device 28 adopts a new selection. To move the counter hooks 26, it is preferable that no external action be exerted on them. By taking all the needles with it, the carriage 56 guarantees that the counter hooks 26 are free.

 Furthermore, a spring 64 acts on the hooks 24 downwards so that they remain in contact with the counter-hooks 26 when the carriage 56 is not in the high position.

 The device also has a positioning detector which includes another permanent magnet 66 and a sensor 68. This detector ensures synchronization between the position of the counter hooks 26 and the position of the needles 20. This device does not allow a new selection of hooks , that is to say a modification of the position of the counter hooks 26, when all the needles 20 are in the high position.

 On the side of the eye 22 of the needle is the weft thread 8. When the needle 20 descends, driven by the carriage 56 and its permanent magnet 60, the thread 8 also descends. However, the wire 8 must not only be placed at a predetermined height, it must also be in a precise position. A guide 70 is then provided.

 This guide 70 is formed by a rod having the shape of a V. The point of the V is oriented downwards and each of the branches of the V is attached by its free end to the lower end of a guide column 54.

 The plane of the V is, in the embodiment shown, inclined about 45 "horizontally.

This inclination can be chosen differently depending on the configuration of the loom.

 The V is placed so that the ends of the branches of the V are substantially at the height of the eye 22 of the needles 20 when the latter are in the high position, while the tip of the V is located substantially above the eye 22 of the needle selected when it is in the down position.

 This guide 70 allows during the downward travel of the needle 20, to move the wire not only vertically but allows to bring the wire in a predetermined position, that where the tip of the V of the guide 70 is located which is fixed. Whatever needle 20 is selected, the corresponding weft thread 8 will always be found in the tip of the V of guide 70.

 The weft thread 8 selected being always at the same predetermined location, it is possible to come and get it there to pass it through the crowd. Any mechanical vector can pick up the weft thread 8: a rigid or flexible lance provided with a clamp at its end, an air flow, a drop of water, etc.

 The translational drive along the guide columns 54 can be controlled by various mechanical means. In the preferred embodiment shown in the drawing, this alternative translational movement is obtained by transformation of a circular movement.

 A pulley 72 is mounted on the housing 16, on the side opposite to the cover 18. This pulley 72 is intended to be driven from a movement of the loom or by an independent electric motor, for example an incremental motor, via a toothed belt.

 The pulley 72 is mounted on a shaft 74 rotating relative to a flange 76 fixed on the housing 16. A bearing 78 is placed between the flange and the shaft 74.

 The shaft 74 is integral with a disc 80 located on the inside of the housing 16. An eccentric pin 82 is mounted on this disc 80. It engages in a groove 84 made in the carriage 56, on the face of the latter opposite the needles 20. A second bearing 86 facilitates the movement of the crankpin 82 in the groove 84.

 When the pulley 72 is driven in rotation, it drives the disc 80 in rotation and the crankpin 82 allows the transformation of this circular movement into an alternative movement of translation of the carriage 56.

 The operation of this weft yarn selection device is then as follows.

 At the start, we consider that the carriage 56 is in the high position. For each stroke of the loom, a weft thread 8 must be selected. The sensor 68 verifies that all the needles 20 are in the high position and then authorizes the hook selection device 28 to make a new selection. All the hooks 24, except the one corresponding to the selected weft thread, face a counter-hook 26.

 The carriage 56 begins to descend. All the needles 20 are driven by the permanent magnet 60 but most of them are stopped by the counter hooks 26 while the needle 20 corresponding to the selected weft thread 8 descends with the carriage 56.

 The weft thread 8 driven by the selected needle 20 is placed in the thread guide 70 which allows it to be positioned in the tip of the V so as to allow it to be taken up by pliers or any other means intended to take the thread with it. frame 8 through the crowd.

 Once the weft thread 8 has been taken and driven, the carriage rises, carrying with it the selected needle.

 Arriving in the high position, the carriage 56 raises all the needles 20 so as to release the counter hooks from any constraint. The sensor 68 then authorizes the hook selection device 28 to take a new configuration.

 It goes without saying that the invention is not limited to the single embodiment described above by way of nonlimiting example; on the contrary, it embraces all its variants.

 Thus, for example, it is possible to provide that only the selected needle does not move and that all of the other needles move. All it takes is a relative movement between the selected needle and the other needles.

 It is also not necessary to use a hook selection device as described. One can imagine a row of needles, each needle of which is associated with an electromagnet which would directly select a needle without the intermediary of counter hooks.

 The needles are not necessarily driven by a magnet. The device as described would work by eliminating the permanent magnet and by associating with each needle a spring exerting a downward stress.

During the downward movement of the carriage the selected needle would then descend with the carriage, the others would remain in place, retained by the counter hooks, while during the movement of raising the carriage, thanks to the shoulder made at the base of the hook, the needle would be pulled up.

 The number of needles shown in the drawing has been reduced to nine for the sake of clarity. However, it is easy for a person skilled in the art to imagine that this device can, in a very small footprint, manage the selection of a much larger number of weft threads, twenty-four for example.

 The shape and orientation of the guide are given by way of example. This guide could be in a plane parallel to the needles, but it could also have a completely different shape, for example a so-called horse saddle shape.

Claims (12)

 1. Weft yarn selection device for a weaving loom comprising needles (20) each having an eye (22) through which a weft yarn (8) passes,  characterized in that the needles (20) are arranged parallel to each other, all the needle eyes (22) being on the same side,  in that means (56, 60) are provided for longitudinally moving one needle (20) relative to the others between an inactive position and a selection position, and  in that the device comprises a guide (70) for weft thread, arranged between the inactive position and the position for selecting the needles and making a weft thread (8) converge towards a predetermined position when a needle (20) passes from the inactive position to the selection position.  2. Selection device according to claim 1, characterized in that the guide (70) consists of a V-shaped rod, the tip of the V being oriented towards the position for selecting the needles.  3. Selection device according to claim 1 or 2, characterized in that the needles (20) are provided with a hook (24) at their end opposite the eye (22).  4. Selection device according to claim 3, characterized in that it is provided with a hook selection device (28).  5. Selection device according to claim 4, characterized in that the hook selection device (28) is provided with counter-hooks (26) which are controlled so as to move between two positions, a selection position in which the hook (24) and the corresponding counter-hook (26) can be engaged with each other and a non-selection position not allowing such an engagement.  6. Selection device according to one of claims 1 to 5, characterized in that the needles (20) are made of a magnetic material,  in that the weft thread selection device comprises a magnet (60) extending perpendicular to the needles (20) and acting on each of them, and  in that the magnet (60) is movable relative to the longitudinal direction of the needles and drives in its stroke the needle (20) through which the selected wire (8) passes.  7. Selection device according to claim 6, characterized in that the magnet (60) is mounted on a mobile carriage (56) guided by two guide columns (54) parallel to the needles (20) and placed on either side 'other of these.  8. Selection device according to claim 7, characterized in that the movable carriage (56) also carries a needle guide (58) in the form of a comb and faces a friction plate (62) throughout its travel .  9. Selection device according to claims 4 and 8, characterized in that the needles (20) have a shoulder near the hooks (24) so that at the end of travel of the movable carriage (56), when the latter moves towards the hooks (24), all the needles (20) are positively driven by the mobile carriage (56).  10 Selection device according to claim 9, characterized in that each needle (20) is prestressed when it is in the inactive position by a spring (64) acting in the direction of movement towards the eye (22) of the needles.  11. Selection device according to one of claims 9 or 10, characterized in that it also comprises a detector (66,68) for positioning the needles (20) in order to ensure synchronization between the position of the needles and the selection of hooks operated by the hook selection device (28).  12. Selection device according to one of claims 6 to 11, characterized in that the reciprocating movement of the magnet (60) is obtained by transformation of a circular movement.